<html>
<head>
    <title>每隔一定时间更换图片</title>

</head>
<body>

<canvas id="ecg" width="751px" height="751px" ></canvas>
</body>
<script language="javascript">
function strMac(a){
    var str6 = a.substr(a.length-6)
    var strr6 = a.substr(0,6)
    var str = str6[4]+str6[5]+":" + str6[2]+str6[3]+":"+str6[0]+str6[1]+":"+strr6[4]+strr6[5]+":"+strr6[2]+strr6[3]+":"+strr6[0]+strr6[1]
    return str;
}
</SCRIPT>
</html>